html, body {
    width: 100%;
    height: 100%;
}
body {
    display: flex;
}
.g-grid {
    position: relative;
    margin: auto;
    width: 401px;
    height: 451px;
    outline: 1px solid #000;
    outline-offset: 5px;
    background:
        linear-gradient(#fff, #fff),
        repeating-linear-gradient(#000, #000 1px, transparent 1px, transparent 50px),
        repeating-linear-gradient(90deg, #000, #000 1px, transparent 1px, transparent 50px),
        repeating-linear-gradient(-45deg, transparent 0, transparent 5px, #fff 5px, #fff 10px),
        linear-gradient(45deg, transparent, 
            transparent calc(50% - 0.5px), 
            #000 calc(50% - 0.5px), 
            #000 calc(50% + 0.5px), 
            transparent calc(50% + 0.5px), 
            transparent 0),
        repeating-linear-gradient(45deg, transparent 0, transparent 5px, #fff 5px, #fff 10px),
        linear-gradient(-45deg, transparent, 
            transparent calc(50% - 0.5px), 
            #000 calc(50% - 0.5px), 
            #000 calc(50% + 0.5px), 
            transparent calc(50% + 0.5px), 
            transparent 0),
        repeating-linear-gradient(-45deg, transparent 0, transparent 5px, #fff 5px, #fff 10px),
        linear-gradient(45deg, transparent, 
            transparent calc(50% - 0.5px), 
            #000 calc(50% - 0.5px), 
            #000 calc(50% + 0.5px), 
            transparent calc(50% + 0.5px), 
            transparent 0),
        repeating-linear-gradient(45deg, transparent 0, transparent 5px, #fff 5px, #fff 10px),
        linear-gradient(-45deg, transparent, 
            transparent calc(50% - 0.5px), 
            #000 calc(50% - 0.5px), 
            #000 calc(50% + 0.5px), 
            transparent calc(50% + 0.5px), 
            transparent 0);
    background-repeat: no-repeat;
    background-size: 
        calc(100% - 2px) 49px, 100% 100%, 100% 100%, 
        // 交叉虚线 1
        100px 100px, 100px 100px, 100px 100px, 100px 100px,
        // 交叉虚线 2
        100px 100px, 100px 100px, 100px 100px, 100px 100px;
    background-position: 
        1px 201px, 0 0, 0 0, 
        // 交叉虚线 1
        151px 0, 151px 0, 151px 0, 151px 0,
        // 交叉虚线 2
        151px 350px, 151px 350px, 151px 350px, 151px 350px;
    line-height: 451px;
    font-size: 24px;
    text-align: center;
    letter-spacing: 12px;
    white-space: pre-wrap;
    
    &::before {
        content: "";
        position: absolute;
        top: 95px;
        left: 35px;
        width: 10px;
        height: 1px;
        background: #000;
        color: #000;
        box-shadow: 
            20px 0, 0 10px, 20px 10px,
            300px 0, 320px 0, 300px 10px, 320px 10px,
            -30px 50px, -30px 60px,
            50px 50px, 50px 60px, 70px 50px, 70px 60px,
            150px 50px, 150px 60px, 170px 50px, 170px 60px,
            250px 50px, 250px 60px, 270px 50px, 270px 60px,
            350px 50px, 350px 60px;
        -webkit-box-reflect: below 259px;
    }
    &::after {
        content: "";
        position: absolute;
        top: 85px;
        left: 45px;
        width: 1px;
        height: 10px;
        background: #000;
        color: #000;
        box-shadow: 
            10px 0, 0 20px, 10px 20px,
            300px 0px, 300px 20px, 310px 0, 310px 20px,
            -40px 50px, -40px 70px,
            50px 50px, 50px 70px, 60px 50px, 60px 70px,
            150px 50px, 150px 70px, 160px 50px, 160px 70px,
            250px 50px, 250px 70px, 260px 50px, 260px 70px,
            350px 50px, 350px 70px;
        -webkit-box-reflect: below 260px;
    }
}